Well I have to say I am surprised by the poll results in respect what I intended to ask but also see that I was not as specific as needed in my poll question.

It seems a lot of people use trickle chargers / battery tenders and looking back at the poll question, this actually doesn't surprise me. Heck I used to use a Battery Tender on my motorcycle since it never really got any road time.

Although, what I guess I was really trying to ask was "How many people use a trickle charger / battery tender on their daily drivers?" Maybe another poll is in order, maybe not.

Last night I finally got a battery charger / maintainer for my daily driver.
I really never thought that would be needed for a daily driver but it seems this BMW is a different beast. I had things start turning off again so I knew the battery was probably low. I checked the battery about an hour after I got home and it was sitting at 12.2V. The tester estimate it was 50% charged. Gave it a charge last night but it only got to 99% complete before I needed to disconnect it. Very curious to see what it thinks the battery is at when I get home tonight.

Personally I think the battery is done which seems unbelievable for a car that only 2 years 1 month old.

Your battery twice has discharged to the point of no return. You can keep it alive for a while using the tender all the time but because of that it has built up sulfate on the plates.
Some people suggest shocking the battery to remove the sulfate but I will not do that. Your car is an electronic beast and as such locking the car shuts down the DME which will pulse the car every 4 hours for an entire status. Locking the car puts everything to sleep but the IBS.
This car has an overly complex charging system and heavy demand on the 180 watt alternator.
This is why BMW wanted to go with a 48 VDC charging system but abandoned it since it posed too high a safety risk according to BMW.
My 2007 is past 6 years battery life because of my battery tender and my M3 has now reached 9 years with the use of a battery tender.
I think you will get more use out of your battery which is pretty close to dead because the tender will keep it topped up as best it can. Since you had one for your motorcycle I am sure it must have helped that battery...

Yes, I am worried this battery is pretty much a goner. I check the next day and it was at 12.4V and 70%. I let it charge to 100% but haven't touched it since.

With the motorcycle the battery tender was the ticket. It worked really well at keeping up the battery and was pretty easy to deal with the 1-2 times a month I used the motorcycle. The really problem for me with the battery tender on this car is that it's my daily driver for at least Monday thru Friday. On the weekend it either comes out for a nice long cruise or sits in the garage if we need the SUV. Connecting and disconnecting the tender everyday during the week is going to get old very very fast!

I've given heavy thought to selling this car and just getting something else but the car isn't worth dirt right now. It seems I can only get a little over half the purchase price and it's only 2 years old with ~20K miles.

The Warranty booklet said if driving less than 10 miles per trip and no highway miles, you may have this problem... But if you are not...
Felt your pain, you are under warranty right!? may be a power leakage test to see if there are electronic modules drawing power after the car goes to sleep. If leakage, Dealer should fix it under Warranty.
My 2006 e90 still has the Original battery. 7 1/2 years battery life.
Daily commute 24 miles, non Idrive. Use a trickle charger(12V/1.5A) once a month or whenever out for a long trip.

Well that's the thing, per the warranty booklet, I am just into the problem area. As I wrote here, my "per trip" commute is just less than 10 miles at about 9.7 miles. I still think this should be enough as I never had a problem with my old car and it's old battery in the four years prior with the same commute.

I am rather blown away that in two years I am having these kinds of problems. I am really hoping this has something to do with the battery cable recall. I just got my letter a little bit ago but haven't had time to go in yet. Although I somehow think it's probably more due to BMW's Brake Energy Regeneration systems which I discussed here. I wish I could just turn that system off and let it charge normally.

I have a short commute so about once a month I use my BMW battery charger overnight. It always seems to need charging and sometimes it takes longer than overnight to fully recharge. I am guessing that your battery issues will be solved if you start using a battery charger regularly.

And make sure to buy a smart battery charger that will not overcharge your battery. All of the good ones have the ability to only charge when needed and not to overcharge and harm the battery.

BMW's on demand charging scheme should cover the short trip condition, focus on the Energy saving gadgets without getting the basic charging scheme working properly resulting in a premature battery failure; consider it is a design fault which the BMW owners should not bear BMW's blunder, how hard is it to charge the battery to good level whenever the Engine is on for the first 10 miles? Update the SW may be, BMW.